Not Applicable.
Not Applicable.
1. Field of the Invention
The invention is generally related to devices which facilitate operations in fluid and hydrocarbon production; and, more particularly, the invention relates to devices which aid in the positioning of one piece of casing or tubing with respect to another.
2. Description of the Related Art
For onshore and offshore fluid production operations (for example, hydrocarbon production), at times it is necessary to install a smaller diameter casing within larger diameter tubing, such as a conductor pipe, a well head, another casing or the like. To facilitate the placement of the smaller diameter casing in the larger diameter tubing, wedge-like slips are well known in the art. However, at times, the smaller diameter casing lies in a non-central location within the outer pipe. In order to install the slips, the casing must be centrally aligned.
In drilling operations, past and present, certain basic procedures apply. A drilling rig, onshore or offshore, bores a hole in the ground to a specified objective depth where natural resources are projected to exist. This drilling is not always accomplished by simply drilling a single hole with a single diameter, but rather can be a string of holes (for example, two or more) with varying diameters.
In the commencement of a well, a large diameter pipe known as a conductor pipe is driven into the ground or ocean floor to a depth of anywhere from one to three-hundred feet or more under the surface (ground/ocean floor level). After the conductor pipe is driven, a large diameter holexe2x80x94known as a surface holexe2x80x94is drilled through the conductor pipe to a pre-specified depth (typical depths being up to 2,000 feet or more under the surface). Next, a string of pipe called xe2x80x9csurface casingxe2x80x9d is run through the conductor pipe and surface hole, from the surface to the bottom of the surface hole. This string of pipe is cemented into the earth""s crust, and then cut off at the surface above the conductor pipe. Next, a surface wellhead assembly, called the xe2x80x9cAxe2x80x9d section, is placed at the surface on top of the surface casing, whereupon the xe2x80x9cAxe2x80x9d section is secured to the surface casing by welding or other special techniques.
After the securing of the xe2x80x9cAxe2x80x9d section, a blowout preventer is affixed to the top of the xe2x80x9cAxe2x80x9d section. The blowout preventer, after being secured, is tested. If the blowout preventer functions, drilling activity commences.
In the commencement of drilling activity, a smaller hole is drilled through the larger surface casing to a deeper specified depth. Then, smaller diameter casing is run from the surface to a specified depth and again cemented into the earth""s crust. Next, the string of casing is suspended on the xe2x80x9cAxe2x80x9d section and surface casing to avoid collapse. To accomplish this, the blowout preventer is uncoupled and lifted to allow working clearance above the xe2x80x9cAxe2x80x9d section. A set of casing slips are placed around the subject smaller diameter casing and lowered into the xe2x80x9cAxe2x80x9d section top. The xe2x80x9cAxe2x80x9d section top has a special low tolerance bowl for receiving the casing slips at its top section. In order to place these slips into the bowl of the xe2x80x9cAxe2x80x9d section receptacle, the smaller diameter casing must be perfectly centered within the xe2x80x9cAxe2x80x9d section. However, the problem in most cases is that the casing is not centered in the xe2x80x9cAxe2x80x9d section, thus requiring centering by force. Typical methods, prior to the present invention, include the use of one of the drilling rig""s winch lines. Such a method involves attempts to find a direct point for pulling in order to center the casing. The use of such a device and methods are not only time consuming, but can also be very dangerous.
While this basic illustration has been described in reference to an xe2x80x9cAxe2x80x9d section, the process may be repeated in the course of a well through xe2x80x9cBxe2x80x9d, xe2x80x9cCxe2x80x9d, xe2x80x9cDxe2x80x9d, etc. sections.
For offshore operations, safety and time consumption can become even a greater concern. In such offshore operationsxe2x80x94for example, in a jack up rigxe2x80x94the wellhead equipment lies below leverage points. Trying to find a point for pulling (in order to center the casing) becomes very difficult, if not impossible. Sometimes, the BOP is rocked against the casing in an attempt to jar the casing to the center point. This is not only extremely dangerous, but can also cause the support lines of the suspended BOP to break, dropping the BOP on personnel attempting to land the slips. On fixed platforms, where various production lines, other wellheads, etc. are in place, the temptation and sometimes practice is to use these as leverage points which can cause many potential dangers.
Another extremely important issue with regards to safety involves the time the blowout preventer (BOP) is uncoupled from the wellhead. The longer the duration of such uncoupling, the more likely that well control may be imperiled. Thus, the reduction of time in centering the casing becomes an issue.
The present invention in several embodiments increases the safety and reduces the centering task time. In essence, the centering tool assembly offers the following:
I. Safety and Reliability
II. Reduced Risk
III. Economicsxe2x80x94Saved Rig and Operations Time
IV. Overall Comprehensive Safety
In one embodiment of the invention, a centering tool assembly utilizes an actuator, baseplate, power source, support tube, and reaction studs to help centrally position a casing within an outer pipe. The baseplate is arranged and designed to couple to the outer pipe. The actuator is either pre-coupled to the baseplate or coupled to the baseplate after the baseplate couples to the outer pipe. The support tube is arranged and designed to vertically adjust and provide support for the actuator. The power source actuates the actuator, which provides a force on the casing, moving it into a desired position, typically a central position. The reaction studs help stabilize the centering tool assembly during the application of the actuation force.
Various other embodiments of the centering tool assembly are also disclosed. In some of the embodiments, the reaction studs are either not required at all or are replaced with other counteracting members. In yet another embodiment, the centering tool assembly may be used to pull the casing into the desired position.
Additionally, a method for positioning a casing into a desired position within an outer pipe involves coupling a baseplate to the outer pipe. An actuator is coupled to the baseplate, prior to or after said baseplate coupling. Then, the actuator may be vertically adjusted via a support tube. The actuator is activated via a power source and the casing is forced into the desired position.